Variable cam timing (VCT) is used in engines to advance or retard intake and/or exhaust valve timing. Consequently, intake and/or exhaust valve timing may be adjusted based on engine operating conditions to increase combustion efficiency and decrease emissions, if desired. Additionally, engine power output may be increased across a wider range of engine operating conditions.
Locking mechanisms in VCT systems have been developed to lock the VCT system in a desired base configuration when there is insufficient oil pressure to operate the VCT system. For example, U.S. Pat. No. 5,823,152 discloses an angular phase control apparatus for an engine including a tapered locking member configured to mate with an engaging bore to lock the apparatus in a desired angular position.
The Inventors have recognized several drawbacks with the valve timing control apparatus disclosed in U.S. Pat. No. 5,823,152. Manufacturing the locking device disclosed in U.S. Pat. No. 5,823,152 may be costly due to the small tolerances of the tapered locking member and the tapered bore. Additionally, the tapered locking member may become disengaged, due to air pressure, for example. Consequently, the partially disengaged member may move back and forth (e.g., rattle) in an engaging bore receiving the locking member. As a result, the noise, vibration, and harshness (NVH) in the vehicle may be increased, thereby decreasing customer satisfaction and component longevity. Furthermore, the locking member disclosed in U.S. Pat. No. 5,823,152 may become stuck in the engaging bore due to the tapered matting. As a result, phase control functionality may be delayed or inhibited, thereby decreasing combustion efficiency and increasing emissions.
The inventors herein have recognized the above issues and developed a phase control apparatus in a VCT system of an engine is described herein. The phase control apparatus includes a locking pin coupled to a vane, the locking pin extending into a locking pin recess in a cover plate in a locked configuration, the locking pin and locking pin recess having backlash and a housing at least partially enclosing the vane and spaced away from the vane forming a gap in the locked configuration.
The phase control apparatus includes a locking pin coupled to a vane, the locking pin extending into a locking pin recess in a cover plate in a locked configuration, the locking pin and locking pin recess having a backlash and a housing at least partially enclosing the vane and spaced away from the vane forming a gap in the locked configuration.
When the housing is spaced away from the vane in a locked configuration the vibration caused by the contact between the vane and the housing is substantially reduced (e.g., eliminated). In this way, NVH in the engine is reduced, thereby increasing customer satisfaction and component longevity when compared to VCT systems having the housing in direct contact with a vane in a locked configuration.
In one example, the backlash may be less than the gap between the housing and the vane. In this way, the movement of the locking pin in the locking pin recess does not cause the vane to contact the housing in a locked configuration. As a result, NVH is reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.